Perhaps the answer would be to elect the President, auction Senate seats and select House members by lottery. This might produce a wider range of views in the US political system, than if all officeholders are bought and paid for by the rich, in elections which only those approved of by the rich and powerful can enter.
The other answer is to amend the constitution to impose very strict expenditure limits on candidates, require exclusive public funding and mandate tight restrictions on what third parties can spend to affect elections. This would be pretty revolutionary by American standards, but is a more extreme version of the sort of thing most democracies try to do to keep elections fair.
why not replace democratic elections with sale of offices by auction?
That would be a step backwards from the present system. Now those with the money get to decide who will run and have a tacit veto over their positions and actions--all without leaving much evidence behind. Then when things go south they can tell the general public: "Well, you elected these fools." And so we did.
As the Dutch said while fighting the Spanish: "It is not necessary to have hope in order to persevere."
At worst democratic election provides a way of limiting corrupt politician A's period of looting the treasury, even if it just provides corrupt politician B with his turn at the trough.
So you do not believe after all in transparency in government? The Fates are kind.